Security researchers have recently discovered a botnet with a novel defense against takedowns. Normally, authorities can disable a botnet by taking over its command-and-control server. With nowhere to go for instructions, the botnet is rendered useless. But over the years, botnet designers have come up with ways to make this counterattack harder. Now the content-delivery network Akamai has reported on a new method: a botnet that uses the Bitcoin blockchain ledger. Since the blockchain is globally accessible and hard to take down, the botnet’s operators appear to be safe.
It’s best to avoid explaining the mathematics of Bitcoin’s blockchain, but to understand the colossal implications here, you need to understand one concept. Blockchains are a type of “distributed ledger”: a record of all transactions since the beginning, and everyone using the blockchain needs to have access to — and reference — a copy of it. What if someone puts illegal material in the blockchain? Either everyone has a copy of it, or the blockchain’s security fails.
To be fair, not absolutely everyone who uses a blockchain holds a copy of the entire ledger. Many who buy cryptocurrencies like Bitcoin and Ethereum don’t bother using the ledger to verify their purchase. Many don’t actually hold the currency outright, and instead trust an exchange to do the transactions and hold the coins. But people need to continually verify the blockchain’s history on the ledger for the system to be secure. If they stopped, then it would be trivial to forge coins. That’s how the system works.